Alternating-current rectifier



Oct. 28, 1930. H. G. ANDRE ALTERNATING CURRENT RECTIFIER Filed Oct. 1, 1926 fizz/@7580? 718727 5 6 Patented Oct. 28, 1930 UNITED STATES PATENT OFFICE HENRI G. ANDRE, 0F PARIS, FRANCE ALTERNQTING-GURRENT RECTIFIER Application filed October 1, 1926. Serial No. 138,928.

The present invention relates to alternating current rectifiers and more particularly to improvements in rectifier-s of the form disclosed in my application Serial No. 749,214.

The primary object of theinvention is to provide a form of alternating current rectifier which has a greater life than rectifiers heretofore produced and which is so constructed as to'practically avoid short circuiting or otherwise injuring the electrodes.

Another object of the invention is to provide a rectifier in which a plurality of electrodes are employed in such a manner that if one or more of them should become broken or short circuited, the device will still beable to operate or function and the efliciency thereof may thus be maintained during operation. v

A further object of the invention is to provide a rectifier of the form above referred to in which the acid or other liquid employed in the device may be retained therein without danger of leakage or of losing liquid when the apparatus is turned or held in a position other than the upright position.

Another object of the invention is to provide a form of rectifier containing a liquid of low conductivity by which the active rectifying element therein will be regenerated and in which the parts may be readily assembled, and which will be substantially unbreakable through careless handling.

With these and other objects in view, the invention comprises various features hereinafter more fully described and particularly defined in the claims. ,7

My invention is illustrated in its preferred form in the accompanying drawings, in which: Fig. 1 is a sectional view in elevation of my apparatus showing the various parts thereof in their assembled relation;

Fig. 2 is a cross sectional view taken on the line 2-2 of Fig. 1; and

Fig. 3 is across sectional view taken on the line 3-3 of Fig. 1.

.Referring more in detail to the drawings, the numeral 1 indicates a container of' suitable non-conducting material which is made open at the top or upper portion 2 and which is preferably enlarged in its upper half, as indicated in the drawing, so as to permit the parts of the apparatus to be readily placed therein during manufacture or assembly. The container 1 is preferably of glass, but other suitable insulating material may obviously be employed. In the container is placed an electrode 3 adapted to serve as an anode, or apart of the anode, or simply as a conductor to the anode proper, as will be hereinafter more fully explained. As a cathode I preferably employ a plurality of rods or members which are preferably smaller than the electrode or conductor 3 above mentioned.

In the form of the device illustrated in the drawings, I employ seven cathode rods or members 4- which are arranged symmetrically about the central member 3, but it is to be understood that any other suitable mode of arrangement may be employed.

nickel, above mentioned.

The preferred method of connecting and arranging the cathode wiresor rods in the device consists in attaching each of the parts to a molybdenum wire 5 by weldin other equivalent means. The moly denum wires 5 serve as a conducting. means for conducting current, as will hereinafter be more fully described; The cathode rods, or rods comprising the cathode, are each preferably inserted in a separate glass tube 6 of suitable diameter and length, and are preferably fused in place in the tubes 6 so as to prevent shifting of the cathode rods after they have been The molybdenum wires 5 attached to each of the metal rods are preferably brought together s as to form a comfpassed through adjusted in place.

mon conductor after 1 bei openings in disk 7, of silver or other conducting material. By this means the desired conductivity of the cathode leads and the desired rigidity in structure are maintained. The molybdenum wires 5 may be twisted together or otherwise brought to a single point and are preferablythereafter attached to a suitable conductor 8 at the. outside of the container 1, the twisted wires 5 being brought. upwardly through an opening 9 in a stopper 10 which serves as a closure member for the top of the container 1. The stopper 10 may be of rubber or other suitable material.

The conductor or metal anode 3 is preferably of silver or other metal whose oxide is a good conductor of electricity. The anode may be held in place in a tube 11 of insulating material, such as glass, which preferably serves also to hold the lead wire 12 attached thereto. The tube 11 may be located centrally of the'device and may be held in posi;

tion in a central opening in the metal disk 7 and an opening 13 passing through the rubber stopper 10.

In the lower portion of the receptacle 1 is placed a finely powdered mass of metal15, such as silver, which is preferably in the colloidal state. The finely divided metal serves, during operation of the rectifier, as an anode, the central silver or other metal conductor 3 serving more particularly as a lead to the colloidal mass althoughunder certain conditions of the rectifier it may serve also as an anode. Any suitable amount of the powdered silver, or other colloidal or finely divided metal, may be employed in the container 1,

' although an amount such as to bring it up to about the level 1414, as indicated in Fig. 1 is preferablyused. A larger or smaller amount may be employed, if desired, as will be apparent; Above the layer of powdered metallic substance 15 is placed a layer of sand 7 or silicon'dioxide 16 which serves when acid or other liquid is introduced to hold a suitable amount thereof. The sand or other suitable porous material serves as a reservoir and to feed the acid or other liquid to the finely divided or colloidal material should a part of the liquid therein be decomposed or otherwise lost. Above the sand layer 16 is preferably placed an asbestos-"ring 17, which after the acid or other liquid has been introduced into the receptacle, and a suitable amount thereof has been absorbed into the powdered silver or other colloidal metal and into the sand layer, absorbs the excess of acid or liquid'into its pores. It is to be understood that the porous asbestos material does not act as a reser-. voir, but merely to take up the excess of acid or other liquid, whereby if the apparatus should become overturned, or if it should be held in a position other than the upright position, there would be no tendency of liquid to escape or to be removed from the device.

V In the opening 9 in which the lead wire '5 passes to the exterior of the receptacle, I- preferably place a drop of oil so as to prevent acfrom the interior of the device, thus preventing the development of internal pressure in the apparatus.

The device is preferably encased in a suitable casing 18 of brass or other metal so as to prevent breakage of the glass receptacle and other. breakable parts of the device. A base or socket 19 of brass or other suitable metal may form a part of the casing 18, so that the device may be readily secured in place in the usual way.

In order to supply the liquid to the device during assembly a hypodermic needle is preferably used, whereby the acid or other 'liquid may be directed into the central portion of the device in which the liquid functions. The acid or other liquid is preferably put into place before the parts are completely assembled, this material being more easily injected. after the electrodes have been put into place, but before the stopper or cover portion 7 has been inserted into the receptacle 1.

The liquid employed is preferably one of low conductivity and one serving as an oxidizing means for the cathode material so as to form an oxide film or layer of low conductance. I may employ sulfuric acid or sulfuric acid containing sulfuric anhydride, or I may desire to employ phosphoric acid which has also a low conductivity, and a high oxidiz-' ingpower. I may also employ if desired, concentrated sulfuric acid containing phosphoric a'nhydride or other suitable oxidizing liquids of low conductivity.

The operation of my device is not wholly understood from the theoretical standpoint, but I believe, however, that the operation proceeds substantially as follows:

When an alternating current is passed to the apparatus, the positive current first flows from the anode to the cathode withinthe device; or in the device illustrated, from the silver conductor 3 to the silver colloidal material whiclrconstitutes theanode; and from. thence to the one or more of the various nickel cathodes and from thence through the molybdenum wire leads to the lead 8, etc. During the passage ofthis current it is probable that small particles of metal are removed from the-silver rod or conductor 3 and go into suspension or pass into the colloidal state in the liquid at the bottom of the receptacle. If during the initial action of the current any hydrogen is evolved tendmg to produce a reduction around the oathode this action will be neutralized or com-' pensated for on reversal of the current. Furis only a side reaction in the case in which silver is employed as the anode material.

,On reversal of the current, in which the current flows from the cathode rods to the colloidal silver, there is a greater or lesser oxidation which takes place at these smaller rod electrodes, which now constitute the .anodes, and'a film of oxide, such as nickel oxide, in case nickel or ferro nickel rods are used, is formed over these electrodes. The

formation of oxide of nickel or other insulating film or layer continues until a substantially complete surface membrane of the oxide; is formed around the electrodes. WhileI have explained the operation on the basis of fairly complete destruction and reformation of the various films during each cycle, it is probable that only a portion of the film is thus involved. During the passage of current the membrane or layer of nickel or other oxide permits the fiow of electrons in a direction from the nickel containing electrodes to the anode but serves as a barrier or filtering screen to prevent passage of electrons from the silver anode to the cathodes. The apparatus serves, therefore, to rectify a current or to provide for :current moving in one direction only.

If during the operation of the device there appear places where the film is thin or ruptured, the resistance would immediately decrease causing an increased travel of electrons at these points with consequent augmentation of film until the entire surface is rendered uniform'. Hence the cathode takes on a film o'f such character which offers uniformity of operating. characteristic throughout its life It is to be understood that various modifications or changes may be made in the device above described without departing from the spirit orscope of the invention as defined im the claims. 7

Furthermore, although the theory of action has been set forth, which is believed to satisfactorily account for the operation of my device, it'is possible that some other explanation of the phenomena may be formed to more satisfactorily account for the various reactions taking place during operation and I do not therefore, desire to be limited in any manner by the theory as above set forth. While I have ascribed the rectifying function as belonging to thefilm on cathode, there appears to be evidence of a sulphide existing on the silver anode which may also aid in the rectifying process. From theforegoing it will be obvious that films on the cathode cathode is rendered inoperativef Further more, in place of asbestos as an absorbent for the excess acid or other liquid, I might employ a layer of plaster of Paris which I have found to be satisfactory for the purpose.

I claim.

' 1. In a rectifier, the combination of a finely divided anode, a film-forming cathode associated therewith and consisting of a plurality of interconnected elements and means including an oxidation product on the cathode for permitting passage of current between electrodes in one direction only and a slightly ionizable liquid for deriving said oxidation product. 7

2. In a rectifier, the combination of a finely divided anode, a film-forming cathode associated therewith and consisting of a plurality of interconnected elements and means including an oxidation product on the cathode for permitting passage of current between electrodes in one direction only and an acid of low conductivity interposed between said anode and cathode for deriving said oxidation product.

3. In a rectifier, the combination of a finely divided anode, a film-forming cathode associated therewith andconsisting of a plurality of elements arranged about the anode and a unilaterally conducting medium interposed between the cathode and anode whereby rectification is obtained. a l

'4. Ina rectifier, the combination of a container of insulating material, an anode in subdivided form, a film-forming cathode associated therewith, means including a slightly ionizable liquid operating in conjunction with said anode and cathode to cause unidirectional flow of current, a layer of ab- 7 sorbent material constituting a reservoir for the liquid superimposed upon said anode, all of said elements being located in said container.

5. In a rectifier, a receptacle of insulating directional fiow of current, a layer of siliceous material constituting a reservoir for the liq- I uid located adjacent to said anode and an absorbing layer superimposed upon said silic eous material to free the container of excess liquid. 1

6. In a rectifier, a receptacle closed except for a small aperture and containing the following in combination, an anode, a portion of Whichis in sub-divided form, a film-forming cathode associated therewith, low conductivity liquid means operating in conjunction I With said anode and cathode to cause unidirectional fiow of current, such operation causing the evolutlon of gas and means located 1n said aperture whereby the gas 15 expelled but access of moisture to the interior is prevented.

7. As an article of manufacture, an elec-. trode contalnmg silver, a second electrode 4 containing nickel, and comprising a pluralitv of interconnected portions surrounding the silver electrode, all mounted in a receptacle.

.8. A rectifier comprising a finely divided anode, an oxidizing acid of low ionization, and acathode comprising an alloy of iron and silicon in a divided form. I

' 9. A rectifier comprising a finely divided anode, an electrolyte, a film-forming cathode in divided form and means comprising a plurality of layers of porous substances for retaining the electrolyte in the desired place.

10. A rectifier comprising a cup shaped container, a finely divided anode atthe bottom thereof, a centrally disposed lead for said anode, inter-connected cathodes sur-- rounding said anode'lead, an electrolyteof low conductivity, and means including a plurality of layers of absorbent materials 'for retaining said electrolyte.

11. A rectifier comprising a finely divided anode and a plurality of cathodes, means for connecting said cathodes to a common terminal, said means comprising means for electrically isolating any cathode up n a short circuit.

Signed by me at Boston, Massachusetts, this 17th day of September, 1926.

HENRI G. ANDRE. 

